scholarly journals Electrodeposited Hydroxyapatite-Based Biocoatings: Recent Progress and Future Challenges

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 110
Author(s):  
Mir Saman Safavi ◽  
Frank C. Walsh ◽  
Maria A. Surmeneva ◽  
Roman A. Surmenev ◽  
Jafar Khalil-Allafi
Keyword(s):  
Recent Progress ◽  
Tribological Behavior ◽  
Metallic Materials ◽  
Industrial Processing ◽  
Component Size ◽  
Polymeric Particles ◽  
Operational Variables ◽  
Wide Range ◽  
Future Challenges ◽  
Coating Methods

Hydroxyapatite has become an important coating material for bioimplants, following the introduction of synthetic HAp in the 1950s. The HAp coatings require controlled surface roughness/porosity, adequate corrosion resistance and need to show favorable tribological behavior. The deposition rate must be sufficiently fast and the coating technique needs to be applied at different scales on substrates having a diverse structure, composition, size, and shape. A detailed overview of dry and wet coating methods is given. The benefits of electrodeposition include controlled thickness and morphology, ability to coat a wide range of component size/shape and ease of industrial processing. Pulsed current and potential techniques have provided denser and more uniform coatings on different metallic materials/implants. The mechanism of HAp electrodeposition is considered and the effect of operational variables on deposit properties is highlighted. The most recent progress in the field is critically reviewed. Developments in mineral substituted and included particle, composite HAp coatings, including those reinforced by metallic, ceramic and polymeric particles; carbon nanotubes, modified graphenes, chitosan, and heparin, are considered in detail. Technical challenges which deserve further research are identified and a forward look in the field of the electrodeposited HAp coatings is taken.

The chemistry of 4-(dicyanomethylene)-3-methyl-l-phenyl-2-pyrazoline-5- ones as a privileged scaffold in synthesis of heterocycles

2020 ◽  
Vol 17 ◽  
Author(s):  
Mohsen A.-M. Gomaa ◽  
Huda A. Ali
Keyword(s):  
Building Block ◽  
Heterocyclic Compounds ◽  
Recent Progress ◽  
Reaction Conditions ◽  
Azacrown Ethers ◽  
Wide Range ◽  
Privileged Scaffold ◽  
Number Of Publications ◽  
Near Future

Background : The reactivity of 4-(dicyanomethylene)-3-methyl-l-phenyl-2-pyrazoline-5-one DCNP 1 and its derivatives makes it valuable as a building block for the synthesis of heterocyclic compounds like pyrazolo-imidazoles, - thiazoles, spiropyridines, spiropyrroles, spiropyrans and others. As a number of publications have reported on the reactivity of DCNP and its derivatives, we compiled some features of this interesting molecule. Objective: This article aims to review the preparation of DCNP, its reactivity and application in heterocyclic and dyes synthesis. Conclusion: In this review we have provided an overview of recent progress in the chemistry of DCNP and its significance in synthesis of various classes of heterocyclic compounds and dyes. The unique reactivity of DCNP offers unprecedentedly mild reaction conditions for the generation of versatile cynomethylene dyes from a wide range of precursors including amines, α-aminocarboxylic acids, their esters, phenols, malononitriles and azacrown ethers. We anticipate that more innovative transformations involving DCNP will continue to emerge in the near future.

scholarly journals Recent progress on the corrosion behavior of metallic materials in HF solution

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hailong Dai ◽  
Shouwen Shi ◽  
Lin Yang ◽  
Can Guo ◽  
Xu Chen
Keyword(s):  
Environmental Factors ◽  
Stainless Steels ◽  
Hydrofluoric Acid ◽  
Recent Progress ◽  
Future Research ◽  
Fluoride Ion ◽  
Metallic Materials ◽  
Chemical Coupling ◽  
Corrosion Behaviors ◽  
Corrosion Mechanisms

Abstract Hydrofluoric acid (HF) or fluoride ion corrosion issues are often encountered in many fields, which have attracted extensive research due to its strong corrosiveness. In this paper, a critical review is presented based on recent progress on HF corrosion. In view of the discrepancy of fluoride ion compared with other ions, the special attack characteristics of fluoride ion are firstly discussed. Afterwards, the corrosion mechanisms of stainless steels, nickel-based alloys, and titanium alloys in HF solution or fluoride ion-containing environment are reviewed, and three typical corrosion behaviors are summarized, which are essentially weakening process of passivation of metallic materials. The effects of influencing factors (e.g. alloying elements, environmental factors, and stress, etc.) on HF corrosion are also discussed, which involve changes in passivation mechanism, the influence of HF attack mode and multiple damage mechanisms due to mechanical–chemical coupling. Finally, future research works on HF corrosion are proposed.

scholarly journals Using chemical biology to assess and modulate mitochondria: progress and challenges

2017 ◽  
Vol 7 (2) ◽  
pp. 20160151 ◽  
Author(s):  
Angela Logan ◽  
Michael P. Murphy
Keyword(s):  
Mitochondrial Function ◽  
Chemical Biology ◽  
Biomedical Sciences ◽  
Interdisciplinary Approaches ◽  
Wide Range ◽  
Challenges And Opportunities ◽  
Future Challenges ◽  
The Many ◽  
Opening Up

Our understanding of the role of mitochondria in biomedical sciences has expanded considerably over the past decade. In addition to their well-known metabolic roles, mitochondrial are also central to signalling for various processes through the generation of signals such as ROS and metabolites that affect cellular homeostasis, as well as other processes such as cell death and inflammation. Thus, mitochondrial function and dysfunction are central to the health and fate of the cell. Consequently, there is considerable interest in better understanding and assessing the many roles of mitochondria. Furthermore, there is also a growing realization that mitochondrial are a promising drug target in a wide range of pathologies. The application of interdisciplinary approaches at the interface between chemistry and biology are opening up new opportunities to understand mitochondrial function and in assessing the role of the organelle in biology. This work and the experience thus gained are leading to the development of new classes of therapies. Here, we overview the progress that has been made to date on exploring the chemical biology of the organelle and then focus on future challenges and opportunities that face this rapidly developing field.

The Processing of Ultrafine-Grained Materials Using High-Pressure Torsion

2007 ◽  
Vol 558-559 ◽  
pp. 1283-1294 ◽  
Author(s):  
Cheng Xu ◽  
Z. Horita ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
High Pressure ◽  
High Pressure Torsion ◽  
Metallic Materials ◽  
Grain Sizes ◽  
Ultrafine Grained ◽  
Wide Range ◽  
Ultrafine Grained Materials ◽  
Thin Disks

It is now well-established that processing through the application of severe plastic deformation (SPD) leads to a significant reduction in the grain size of a wide range of metallic materials. This paper examines the fabrication of ultrafine-grained materials using high-pressure torsion (HPT) where this process is attractive because it leads to exceptional grain refinement with grain sizes that often lie in the nanometer or submicrometer ranges. Two aspects of HPT are examined. First, processing by HPT is usually confined to samples in the form of very thin disks but recent experiments demonstrate the potential for extending HPT also to bulk samples. Second, since the strains imposed in HPT vary with the distance from the center of the disk, it is important to examine the development of inhomogeneities in disk samples processed by HPT.

scholarly journals Aluminum metal matrix composites a review of reinforcement; mechanical and tribological behavior

2018 ◽  
Vol 7 (2.4) ◽  
pp. 117 ◽  
Author(s):  
Pranav Dev Srivyas ◽  
M S. Charoo
Keyword(s):  
Metal Matrix ◽  
Tribological Behavior ◽  
Coefficient Of Thermal Expansion ◽  
Aluminum Matrix ◽  
Weight Ratio ◽  
High Hardness ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Wide Range ◽  
Structural Applications

This review aims to explore the fundamental mechanical and tribological behavior Aluminum matrix composites (AMCs) reinforced with different reinforcements. Aluminum matrix composites are considered to be the new emerging class of materials which are having the tailored properties for specific applications. AMCs are the advanced engineering materials having superior properties as comparison to other conventional aluminum alloys. AMCs exhibits attractive properties such as high hardness, better yield strength, strength to weight ratio, high thermal conductivity, low coefficient of thermal expansion, superior wear and corrosion resistance. In recent times, because of these properties they have repealed keen interest for various potential applications in aerospace, automotive and various other structural applications.. Extensive research and development has been made in the Al-based MMCs with every possible alloy and different reinforcements so as to get the material of desired properties. By suitable use of different reinforcements in the Al metal matrix a wide range of properties combination can be obtained. The fundamental mechanical and tribological behavior of different reinforcements under dry and wet lubricated sliding conditions is recently being studied. It is reported that various reinforcement were successfully employed to decrease friction and wear in various applications. A comprehensive review is provided with the aim to analyze such properties of different reinforcements. 

scholarly journals CubeSat Communications: Recent Advances and Future Challenges

2020 ◽  
Author(s):  
Nasir Saeed ◽  
Ahmed Elzanaty ◽  
Heba Almorad ◽  
Hayssam Dahrouj ◽  
Tareq Y. Al-Naffouri ◽  
...  
Keyword(s):  
Channel Modeling ◽  
Future Research ◽  
New Paradigm ◽  
Earth Remote Sensing ◽  
Research Directions ◽  
Space Industry ◽  
Recent Advances ◽  
Wide Range ◽  
Future Challenges ◽  
Future Research Directions

<pre><pre>Given the increasing number of space-related applications, research in the emerging space industry is becoming more and more attractive. One compelling area of current space research is the design of miniaturized satellites, known as CubeSats, which are enticing because of their numerous applications and low design-and-deployment cost. </pre><pre>The new paradigm of connected space through CubeSats makes possible a wide range of applications, such as Earth remote sensing, space exploration, and rural connectivity.</pre><pre>CubeSats further provide a complementary connectivity solution to the pervasive Internet of Things (IoT) networks, leading to a globally connected cyber-physical system.</pre><pre>This paper presents a holistic overview of various aspects of CubeSat missions and provides a thorough review of the topic from both academic and industrial perspectives.</pre><pre>We further present recent advances in the area of CubeSat communications, with an emphasis on constellation-and-coverage issues, channel modeling, modulation and coding, and networking.</pre><pre>Finally, we identify several future research directions for CubeSat communications, including Internet of space things, low-power long-range networks, and machine learning for CubeSat resource allocation.</pre></pre>

scholarly journals Analysis of the Powertrain Component Size of Electrified Vehicles Commercially Available on the Market

2022 ◽  
Vol 24 (1) ◽  
pp. B74-B86
Author(s):  
Ruzimov Sanjarbek ◽  
Jamshid Mavlonov ◽  
Akmal Mukhitdinov
Keyword(s):  
Mass Production ◽  
Combustion Engine ◽  
Research Literature ◽  
Component Size ◽  
Performance Requirements ◽  
Vehicle Data ◽  
Wide Range ◽  
Insight Into ◽  
Real Vehicle ◽  
Electrified Vehicles

The paper aims to present an analysis of the component sizes of commercially available vehicles with electrified powertrains. The paper provides insight into how the powertrain components (an internal combustion engine, an electric motor and a battery) of mass production electrified vehicles are sized. The data of wide range of mass production electrified vehicles are collected and analyzed. Firstly, the main requirements to performance of a vehicle are described. The power values to meet the main performance requirements are calculated and compared to the real vehicle data. Based on the calculated values of the power requirements the minimum sizes of the powertrain components are derived. The paper highlights how the sizing methodologies, described in the research literature, are implemented in sizing the powertrain of the commercially available electrified vehicles.

Biodegradation of Restorative Metallic Systems

1992 ◽  
Vol 6 (1) ◽  
pp. 32-37 ◽  
Author(s):  
Linda C. Lucas ◽  
Jack E. Lemons
Keyword(s):  
Metallic Materials ◽  
Multicomponent Alloys ◽  
Host Environment ◽  
Surface Conditions ◽  
Dental Restorations ◽  
Wide Range ◽  
Pure Metals ◽  
Metallic Systems

Metallic materials utilized for the construction of intra-oral and implant dental restorations include a wide range of relatively pure metals and multicomponent alloys. Basic corrosion and biodegradation properties of these alloys have been studied by both in vitro and in vivo techniques. These property characteristics have been shown to be dependent on composition and metallurgical state, combinations within a construct, surface conditions, mechanical aspects of function, and the local and systemic host environment. The susceptibility of these metallic materials to various forms of biodegradation will be presented, with emphasis on corrosion.

Probabilistic model of surface layer removal when grinding brittle non-metallic materials

2021 ◽  
Vol 23 (2) ◽  
pp. 6-16
Author(s):  
Sergey Bratan ◽  
◽  
Stanislav Roshchupkin ◽  
Alexander Kharchenko ◽  
Anastasia Chasovitina ◽  
...  
Keyword(s):  
Surface Layer ◽  
Contact Zone ◽  
Probabilistic Model ◽  
Material Removal ◽  
Brittle Materials ◽  
Grinding Wheel ◽  
Metallic Materials ◽  
Deformable Solid ◽  
Metallic Material ◽  
Wide Range

Introduction. The final quality of products is formed during finishing operations, which include the grinding process. It is known that when grinding brittle materials, the cost of grinding work increases significantly. It is possible to reduce the scatter of product quality indicators when grinding brittle materials, as well as to increase the reliability and efficiency of the operation, by choosing the optimal parameters of the technological system based on dynamic models of the process. However, to describe the regularities of the removal of particles of a brittle non-metallic material and the wear of the surface of the grinding wheel in the contact zone, the known models do not allow taking into account the peculiarities of the process in which micro-cutting and brittle chipping of the material are combined. Purpose of the work: to create a new probabilistic model for removing the surface layer when grinding brittle non-metallic materials. The task is to study the laws governing the removal of particles of brittle non-metallic material in the contact zone. In this work, the removal of material in the contact zone as a result of microcutting and brittle chipping is considered as a random event. The research methods are mathematical and physical simulation using the basic provisions of the theory of probability, the laws of distribution of random variables, as well as the theory of cutting and the theory of a deformable solid. Results and discussion. The developed mathematical models make it possible to trace the effect on material removal of the overlap of single cuts on each other when grinding holes in ceramic materials. The proposed dependences show the regularity of stock removal within the arc of contact of the grinding wheel with the workpiece. The considered features of the change in the probability of material removal upon contact of the treated surface with an abrasive tool and the proposed analytical dependences are valid for a wide range of grinding modes, wheel characteristics and a number of other technological factors. The obtained expressions make it possible to find the amount of material removal also for schemes of end, flat and circular external grinding, for which it is necessary to know the amount of removal increment due to brittle fracture during the development of microcracks in the surface layer. One of the ways to determine the magnitude of this increment is to simulate the crack formation process using a computer. The presented results confirm the prospects of the developed approach to simulate the processes of mechanical processing of brittle non-metallic materials.

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